1. Field of the Invention
The present invention relates in general to an improved cleaner for hard surface cleaning applications, including kitchens, bathrooms, tubs and tiles, amongst others, and more particularly to a hard surface cleaning composition having improved cleaning and descaling properties.
2. Background Art
Hard surface cleaning compositions have been known and used in a variety of applications, including bathrooms, kitchens and other areas, particularly for toilets, showers, bathtubs, sinks, tiles, countertops, walls, floors and the like. Often times, hard surfaces accumulate both soap scum stains, which are typically residues of various types of soaps used in a household, as well as hard water stains, which are typically the result of the deposition of calcium, lime or various salts on hard surfaces over the course of time and use of various household surfaces.
Cleaning solutions for these household surfaces have been formulated to address both the removal of soap scum stains, as well as the descaling of hard water stains. In particular, many of these cleaning solutions have employed a combination of components, in a number of instances including strong inorganic acids, organic acids or a combination of both, a surfactant or wetting agent, a solvent and a diluent to address one or both of these types of stains and/or build-ups. The acid component is typically selected to address descaling of hard water stains, while the surfactant component is typically a detergent selected to attack soap scum. Further, other additives have also been used in combination with cleaning formulations to either enhance performance or make a particular formulation more desirable from a visual or odor perspective, such as PH adjusters, stabilizing agents, colorants and fragrances, amongst others.
For instance, Sherry et al., U.S. Pat. No. 6,627,590, discloses an acidic hard surface cleaning composition which includes (1) an alkyl sulfate surfactant containing 10 carbon atoms (comprising about 0.5 wt. % to about 5 wt. % of the solution), (2) one or more organic cleaning solvents (comprising about 1 wt. % to about 6 wt. % of the solution), (3) a mono or polycarboxylic acid (comprising about 3 wt. % to 5 wt. % of the solution) and (4) an aqueous solvent (comprising about 60-90 wt. % of the solution). Additionally, the acidic hard surface cleaner of Sherry et al. may also include a small amount of a anionic and/or nonionic detergent surfactant, preferably an anionic co-surfactant, examples of which include a sulfate or carboxylate hydrophilic head group. The C10 alkyl sulfate preferably takes the form of an ammonium salt or a sodium salt. The organic cleaning solvent is based upon propylene glycol chemistry, preferably selected from the di- and tri-propylene glycol derivates of propyl and butyl alcohol. Citric acid is specified as being the most preferred carboxylic acid and is required by the claims; however, Sherry et al. also discloses the use of other mono or polycarboxylic acids, including acetic acid, glycolic acid, tartaric acid, succinic acid, glutaric acid, adipic acid and mixtures thereof. The cleaning solution has a pH of about 2-5.
Stamm, U.S. Pat. No. 5,925,606, discloses a concentrated acidic liquid detergent composition for cleaning soap scum, lime scale, etc. from hard surfaces. The liquid detergent comprises a carboxylic acid in an amount of 0.25-50 wt. % (preferably 1-25 wt. %), a surfactant in the amount of about 0.05-20 wt. % (preferably 0.1-15 wt. %) and an organic solvent present in the amount of approximately 0.25-20 wt. % (preferably 0.4-10 wt. %). The carboxylic acid is preferably a hydroxy monocarboxylic acid having up to four carbon atoms, with hydroacetic acid listed as being the only specific acid that is indicated as preferred, that is claimed or that is even disclosed. The surfactant is an anionic surfactant, a non-ionic surfactant or a mixture thereof, and may be chosen from alkyl sulfonates, alkyl ether sulfates (such as sodium lauryl sulfate), amongst many others. The organic solvent is preferably a C1 to C6 alkyl ether of either ethylene glycol or propylene glycol and derivates thereof, including propylene glycol monomethyl ether. The formula may also include other additives, such as pH adjustors, stabilizing agents, preservatives, fragrances and dyes.
Rochon et al., U.S. Pat. No. 6,432,395 discloses a cleaning composition containing naturally derived components. The cleaning composition includes three principal components, including an organic acid (comprising 0.004-28 wt. % of the composition), an anionic surfactant (comprising 0.0003-7 wt. % of the solution) and a non-ionic surfactant (comprising 0.0035-36 wt. %) surfactant. The organic acid is a C1-C20 non-fatty carboxylic, dicarboxylic or tricarboxylic acid, preferably lactic acid—although other less preferable naturally derived organic acids such as maleic acid, citric acid, maleic acid, succinic acid, gluconic acid and polyaspartic acid are also disclosed. The anionic surfactant is disclosed as preferably an alkyl glucoester, chosen to provide enhanced hard water surface tolerance, foam stability and improved mildness to the skin. The non-ionic surfactant is preferably an alkyl polyglucoside, although a sorbitan ester can also be used, to provide effective surface tension reduction and detergency. A protein may also be added to reduce skin irritancy, while a naturally derived organic solvent, such as ethanol or naturally derived organic esters, may also be added to the cleaning solution to aid salvation of particularly heavy greasy films or residues.
Urban, U.S. Pub. No. US 2002/0187918 A1, discloses a hard surface cleaning composition having an acidic pH, providing for removal of soap scum stains and having low levels or irritability to the user. The cleaning composition includes an acid sequestrant (comprising about 0.1 to 10 wt. % of the solution), a mixture of hydrophobic and hydrophilic solvents (comprising about 0.1-10 wt. % of the solution), an anionic surfactant (comprising about 0.001-1 wt. % of the solution) and one or more optional components (comprising 0-20 wt. % of the solution). The acid is a combination of citric acid together with another acid effective in the removal of hard water stains, such as sulfonic acid, phosphoric acid, salicylic acid, sorbic acid, sulfamic acid, acetic acid, benzoic acid, boric acid, caproic acid, folic acid, oxilic acid, phosphorous acid, sulfonic acid, maleic acid, adipic acid, lactic acid, gluconic acid and glycolic acid, amongst others. A combination of citric acid and glycolic acid is most preferred. The solvent is a mixture of hydrophobic and hydrophilic solvents which solubilize soap scum and facilitate removal of stains from hard surfaces. The hydrophilic portion of the solvent comprises about 51 to 99% of the total weight of the solvent, and may comprise propylene glycol phenyl ether, ethylene glycol ether, propylene glycol n-butyl ether or other glycol-based ethers, while the hydrophilic portion of the solvent may include alcohols, glycols, acetates, propylene glycols and ethylene glycol n-butyl ethers, amongst others. The anionic surfactant is preferably selected from alkylphenoxybenzene disulfonates, linear alkylphenoxybenzene sulfonates and alkylnaphthalene sulfonates and salts thereof. The optional components can include non-ionic surfactants, forming agents, fragrances, colorants, pH adjusting agents and preservatives, amongst others.
Similarly, Rees et al, U.S. Pat. No. 6,699,825, discloses an acidic hard surface anti-microbial cleaner containing (1) about 0.2 wt. % of an organocarboxylic acid, about 2 wt. % of a volatile solvent selected from a group consisting of n-butyl, benzyl alcohol, phenylethanol and glycol ether solvents. The cleaning composition may also contain 0.1 wt. % of an anionic sulfated or sulfonated surfactants and about 5 wt. % of a co-solvent comprising water soluble monoprotic aliphatic alcohols and glycol ethers.
While these and other prior art hard surface cleaning formulations have been used effectively for cleaning a variety of hard surfaces, it is still desirable to find an improved cleaning solution which addresses both soap scum and the descaling of hard water stains, as well as one which is milder on the skin and has less odor.
It is also desirable to provide a cleaning solution which minimizes and/or eliminates the more corrosive inorganic acids, as well as the more corrosive organic acids, and instead uses less corrosive, but equally effective organic acids to achieve the desired cleaning results.
It is yet further desirable to find a cleaning solution with a specific combination of organic acids, surfactants and solvents which act in a synergistic manner to improve cleaning performance on hard surfaces. These and other objectives of the invention are described herein.